Ocean basins serve as collecting bins for eroded debris that is washed from
continents. Sources of sediment that end up in coastal environments, and ultimately
the deep sea, are: (1) sedimentary debris produced by weathering and erosion
of rocks on land; (2) grains derived from the hard parts of organisms, such
as skeletal debris, shells, and teeth; (3) tiny grains—typically small,
magnetic spheres and silicate chondrules (bit of asteroids originating from
outer space, so-called extraterrestrial debris); (4) material, such as manganese
nodules, that is precipitated by chemical or biochemical reactions in seawater;
and (5) material, such as ash, that is ejected from volcanoes.

To learn more about sediments that make up coastlines, select a shell.